Male touch fasteners are commonly incorporated into molded objects, such as polyurethane foam seating cushions, during a molding process, for securing a fabric cover over the cushion.
Hook and loop touch fasteners, such as those sold under the trademarks “VELCRO” and “ULTRAMATE,” are well known and are used to join two members detachably to each other. This type of fastener has two components. Each has a flexible substrate or base, having one component of the fastening system on the surface thereof One surface typically carries resilient hooks while the other carries loops. When the two surfaces are pressed together they form a releasable engagement.
The hooks can be any of a variety of shapes, including cane-shaped, palm tree-shaped and mushroom-shaped, all of which are well known within the art. As used herein, the terms “hook,” “hook-type” and “hook-like” shall be construed to mean any such configuration of loop-engaging element.
Touch fasteners are used in the manufacture of automobile seats in the attachment of an upholstered seat cover, (“trim cover”), to a polyurethane foam bun. One portion of the separable touch fastener is incorporated into the surface of the polyurethane seat bun during the foam molding process. The mating portion of the separable fastener is attached to the seat cover to provide releasable attachment to the foam seat bun. The separable fastener assembly used in the foam mold for incorporation in the bun surface typically is the hooked or male portion of the separable fastener system. This hook portion has a base carrying resilient hooks on one surface. The surface of the base obverse of the hook-carrying surface may act as an anchoring surface.
In some assemblies a magnetically attractive material is attached to the base to temporarily hold the fastener in a trough or channel of the mold cavity wall, which is equipped with magnets. It is also possible to incorporate magnetically attractive material into the body of the fastener itself, such as in a plastic material that is used to make the fastener.
In other known set-ups, the fastener is secured in the mold by a snug-fit, such as within a trench that is slightly narrower than the fastener, or upon a pedestal that fits into a foam doughnut that carries the fastener, with the doughnut having a smaller inner diameter than the outer diameter of the pedestal.
To form a molded foam product incorporating a touch fastener, the fastener is secured to one surface of a clamshell mold; a chemical mixture, for instance of a diisocyanate and a polyol, is injected into the mold; the mold is closed and clamped shut while the chemicals react and blow to form a flexible foam.
During the foaming process it is useful to keep the foaming resin from flowing between the discrete male fastener elements, and various sealing means have been developed. For example, a protective layer, often in the form of a thin plastic film, may be placed over the resilient hooks (before they are placed in the mold) to prevent incursion of foam into the hooks during the molding process. After molding, the film or other cover is removed to expose the fastener elements. Gaskets have also been provided around the perimeter of touch fastener products, to inhibit foam intrusion into the hook area.
Another challenge to using fasteners of the type described above in connection with molded products, foam or otherwise, is that it is often desirable to attach the fastener to a contoured surface, perhaps one that curves through three dimensions. All of the fasteners described above, in their basic configuration, are made as continuous elongated rectangular sheets, which are typically used as is, or stripped into narrower strips, all of which remain basically rectilinear. Relatively stiff fastener strips can be bent, relatively easily, through two dimensions, out of the plane of the strip. However, bending in the plane of the strip would result in creasing or puckering, as would bending around two or more axes in three dimensions. Bending is further complicated by some fastener element covering schemes, as bending may cause the cover to buckle or separate from the substrate, and thus to fail for its intended purpose.
It is possible to make large planar sheets and cut from them any desired fastener shape. However, this procedure typically results in a relatively high amount of waste material. Another possible solution is to use numerous separate relatively small fasteners, each of which must be separately placed in and fixed to the mold.
Often designers wish to include a relatively deep recess in a fabric covered product, such as in particular, cushions for automobiles, airplanes, boats, etc. A deep recess in the cushion requires a sharp crease in the seat cover, which in turn requires a flexible, unobtrusive means for securing the cover to the deepest recesses of the cushion. The sharper the crease, the narrower must be the fastening device. Using a narrower fastener reduces the area of interface between the fastener and the foam, and also between the two complementary fastener components.